Electrolytic rectifier



p 1930. LE RUE P. BENSHNG 1,775,417

ELECTROLYTIC RECTIFIER Filed May 23, 1925 a I jIIIH m l flw F nsusous ELEETRDLYTE 1 INHGTIVE ELECTRODE I 5| L| c I: N

FICTIVE summons 1 Snow J01 LE RUE P-BENSINE Patented p 9,1930

UNITED STATES PATENTOFFICE v LE nor: 1. mmsnm, or CLEVELAND, 01:10, ASQIGNOB 010mm ouonon r.

- KOELLIKER, or cmvmanm nmon'rs, onro c arucrnormrxc Application filed May as,

My invention relates to electrolytic valves and rectifiers, and particularly to a new and useful element comprising silicon'which I have discovered possesses valve and rectifying action to an extent not possessed by other elements when used and applied to electrical currents of moderate frequencies as exemplified in the customary household lighting systems, for example, an alterna ing current of 110 volts. In many instances, depending upon the particular application, it

i is desirable to transform such currents to still lower voltages, say to volts, and I find that silicon is of especial utility in that connection although I also wish it understood that higher voltages than 110 may operate successfully with my device, and that the commercial application to which silicon is put der the f ollowing conditions: a small piece of silicon was placed in series with an ammeter and several standard dry cells of one and one-half volts potential, respectively, and with three volts, a very low conductance of about 9.25 amperes was observed. Upon increasing the voltage to six volts the our perage rose to one ampere. Using the same piece of silicon and connecting it in series with an ammeter and a transformer of 159 lwatts capacity, the primary taking 110 volts A. G. 69 cycles 3phase, and the secondary of this transformer having variable voltage taps from one and one-half volts to thirty volts, it was observed with three volts that a very slight deflection of the needle of the arm meter tool: place together with a, considerable rise in temperature of the silicon. Upon increasing the voltage to six, the amperage was 0.25 ampere maximum accompanied with a still greater rise in temperature in the piece of silicon. These experiments made it obvious that silicon at low voltages possesses valve and rectifying action without the use 1925. semi m. 32,500.

of an electrol te, and I then experimented with various e ectrolytes and discovered that distinct advanta es are obtained through the use of an electro vte in connection with silicon. Thus when silicon instead of the com-.

manly used elements was made the cathode in connection with an aqueous electrolyte at low voltages better valve and rectification was obtained and the difference was even more apprecialile at higher voltages.

As an exemplification of an electrolytic rectifier embodying my invention, reference may be had to the accompanying drawing in which the single figure is a sectional view of a rectifier cell with the electrodes shown and indicated thereon. 1 have also discovered that most any aqueous electrolyte may he successfully employed with silicon because of the chemical inertness of the element. Thus, I have successfully employed aqueous solutions of the fixed alkaline hydroxides, borates, fluorides, phosphates, carbonates, mineral'acids, including acetic acid. I found that silicon possesses valve and rectifying action in almost all the aqueous solutions of inorganic compounds and is chemically inert even in concentrated hydrofluoric acid. Accordingly, silicon is adaptable "for permanent types of lightning arresters, rectifiers, battery devices and the like. Also the valve and rectifying action of silicon is developed to such an extent that it may be used as a filter and choke for alternatin currents. Therefore, it is one of the most sensitive rectifiers and valves which to my knowledge has thus far been developed. Again, in most types of electric rectifying apparatuses there is a slight seepage of alternating current, and I find that this may be absorbed by metallic silicon, either in the air or when used in connection with aqueous electrolytes. It also appears that because of the low thermal and therefore electrical con- (luctivity of silicon and also because ofits brittleness, silicon must he used in rather large dimensions. When this cannot be done metals and alloys which have a surface coating of silicon may be used. I prefer silicon of high purity, but I also find alloys of silicon, more particularly the form-alloys, adaptable to my purposes. In using an alloy of silicon the silicon is present in suflicient amount to efi'ect rectification, preferably in per onderating amount. For exam la, a desire 1e electrodeof silicon-ferro a1 0y may consist of five to twenty per cent of iron and the balance silicon;-

Summarizing briefly, I desire to make it clear that silicon has exceptional valve and rectifying action-at low voltage and moderate frequencies, and that this power may be increased by the use of aqueous electrolytes, particularly when silicon is used as the oathode and theanode is one of the inert chemical elements of the fourth group according to the Mendcle'effs classification of the chemical elements, for example, either an anode of carbon or lead.

,In vibrating types of rcctifiers where a comparatively low percentage of the current is rectified, the addition of silicon or an element of silicon placed in series with other rectifying elements, will increase and strengthen the rectified current.

What I claim, is:

An electrolytic rectifier for rectifying alternating electric currents of low frequency including an active electrode made of a siliconferro alloy, in which the silicon is present in preponderating amount.

In testimony whereof I aflix my signature.

LE RUE P. BENSING. 

